/*-----------------------------------------
   DIGCLOCK.c -- Digital Clock
                 (c) Charles Petzold, 1998
  -----------------------------------------*/

#include <windows.h>

#define ID_TIMER    1

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
	PSTR szCmdLine, int iCmdShow)
{
	static TCHAR szAppName[] = TEXT ("DigClock") ;
	HWND         hwnd ;
	MSG          msg ;
	WNDCLASS     wndclass ;

	wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
	wndclass.lpfnWndProc   = WndProc ;
	wndclass.cbClsExtra    = 0 ;
	wndclass.cbWndExtra    = 0 ;
	wndclass.hInstance     = hInstance ;
	wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
	wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
	wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
	wndclass.lpszMenuName  = NULL ;
	wndclass.lpszClassName = szAppName ;

	if (!RegisterClass (&wndclass))
	{
		MessageBox (NULL, TEXT ("Program requires Windows NT!"), 
			szAppName, MB_ICONERROR) ;
		return 0 ;
	}

	hwnd = CreateWindow (szAppName, TEXT ("Digital Clock"),
		WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, CW_USEDEFAULT,
		CW_USEDEFAULT, CW_USEDEFAULT,
		NULL, NULL, hInstance, NULL) ;

	ShowWindow (hwnd, iCmdShow) ;
	UpdateWindow (hwnd) ;

	while (GetMessage (&msg, NULL, 0, 0))
	{
		TranslateMessage (&msg) ;
		DispatchMessage (&msg) ;
	}
	return (int)msg.wParam ;
}

void DisplayDigit (HDC hdc, int iNumber)
{
	static BOOL  fSevenSegment [10][7] = {
		1, 1, 1, 0, 1, 1, 1,     // 0
		0, 0, 1, 0, 0, 1, 0,     // 1
		1, 0, 1, 1, 1, 0, 1,     // 2
		1, 0, 1, 1, 0, 1, 1,     // 3
		0, 1, 1, 1, 0, 1, 0,     // 4
		1, 1, 0, 1, 0, 1, 1,     // 5
		1, 1, 0, 1, 1, 1, 1,     // 6
		1, 0, 1, 0, 0, 1, 0,     // 7
		1, 1, 1, 1, 1, 1, 1,     // 8
		1, 1, 1, 1, 0, 1, 1 } ;  // 9
		static POINT ptSegment [7][6] = {
			7,  6,  11,  2,  31,  2,  35,  6,  31, 10,  11, 10,
			6,  7,  10, 11,  10, 31,   6, 35,   2, 31,   2, 11,
			36,  7,  40, 11,  40, 31,  36, 35,  32, 31,  32, 11,
			7, 36,  11, 32,  31, 32,  35, 36,  31, 40,  11, 40,
			6, 37,  10, 41,  10, 61,   6, 65,   2, 61,   2, 41,
			36, 37,  40, 41,  40, 61,  36, 65,  32, 61,  32, 41,
			7, 66,  11, 62,  31, 62,  35, 66,  31, 70,  11, 70 } ;
			int          iSeg ;

			for (iSeg = 0 ; iSeg < 7 ; iSeg++)
				if (fSevenSegment [iNumber][iSeg])
					Polygon (hdc, ptSegment [iSeg], 6) ;
}

void DisplayTwoDigits (HDC hdc, int iNumber, BOOL fSuppress)
{
	if (!fSuppress || (iNumber / 10 != 0))
		DisplayDigit (hdc, iNumber / 10) ;

	OffsetWindowOrgEx (hdc, -42, 0, NULL) ;
	DisplayDigit (hdc, iNumber % 10) ;
	OffsetWindowOrgEx (hdc, -42, 0, NULL) ;
}

void DisplayColon (HDC hdc)
{
	POINT ptColon [2][4] = { 2,  21,  6,  17,  10, 21,  6, 25,
		2,  51,  6,  47,  10, 51,  6, 55 } ;

	Polygon (hdc, ptColon [0], 4) ;
	Polygon (hdc, ptColon [1], 4) ;

	OffsetWindowOrgEx (hdc, -12, 0, NULL) ;
}

void DisplayTime (HDC hdc, BOOL f24Hour, BOOL fSuppress)
{
	SYSTEMTIME st ;

	GetLocalTime (&st) ;

	if (f24Hour)
		DisplayTwoDigits (hdc, st.wHour, fSuppress) ;
	else
		DisplayTwoDigits (hdc, (st.wHour %= 12) ? st.wHour : 12, fSuppress) ;

	DisplayColon (hdc) ;
	DisplayTwoDigits (hdc, st.wMinute, FALSE) ;
	DisplayColon (hdc) ;
	DisplayTwoDigits (hdc, st.wSecond, FALSE) ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static BOOL   f24Hour, fSuppress ;
	static HBRUSH hBrushRed ;
	static int    cxClient, cyClient ;
	HDC           hdc ;
	PAINTSTRUCT   ps ;
	TCHAR         szBuffer [2] ;

	switch (message)
	{
	case WM_CREATE:
		hBrushRed = CreateSolidBrush (RGB (255, 0, 0)) ;
		SetTimer (hwnd, ID_TIMER, 1000, NULL) ;

		// fall through

	case WM_SETTINGCHANGE:
		GetLocaleInfo (LOCALE_USER_DEFAULT, LOCALE_ITIME, szBuffer, 2) ;
		f24Hour = (szBuffer[0] == '1') ;

		GetLocaleInfo (LOCALE_USER_DEFAULT, LOCALE_ITLZERO, szBuffer, 2) ;
		fSuppress = (szBuffer[0] == '0') ;

		InvalidateRect (hwnd, NULL, TRUE) ;
		return 0 ;

	case WM_SIZE:
		cxClient = LOWORD (lParam) ;
		cyClient = HIWORD (lParam) ;
		return 0 ;

	case WM_TIMER:
		InvalidateRect (hwnd, NULL, TRUE) ;
		return 0 ;

	case WM_PAINT:
		hdc = BeginPaint (hwnd, &ps) ;

		SetMapMode (hdc, MM_ISOTROPIC) ;
		SetWindowExtEx (hdc, 276, 72, NULL) ;
		SetViewportExtEx (hdc, cxClient, cyClient, NULL) ;

		SetWindowOrgEx (hdc, 138, 36, NULL) ;
		SetViewportOrgEx (hdc, cxClient / 2, cyClient / 2, NULL) ;

		SelectObject (hdc, GetStockObject (NULL_PEN)) ;
		SelectObject (hdc, hBrushRed) ;

		DisplayTime (hdc, f24Hour, fSuppress) ;

		EndPaint (hwnd, &ps) ;
		return 0 ;

	case WM_DESTROY:
		KillTimer (hwnd, ID_TIMER) ;
		DeleteObject (hBrushRed) ;
		PostQuitMessage (0) ;
		return 0 ;
	}
	return DefWindowProc (hwnd, message, wParam, lParam) ;
}
